Proper maintenance of helicopters includes the task of sampling the fuel for contaminants such as water, bugs, dirt, and the like, on a regularly scheduled basis. Such sampling, for example, is performed on Bell OH-58 helicopters that are used for law enforcement purposes. The fuel tank or sump on each of these aircraft is located in the belly of the fuselage, and the drain valve through which the fuel must be drained is located under the fuselage. Periodically, a small quantity, say about one-half of a quart, is drained from the tank and analyzed. Because the belly of the aircraft where the drain valve is located is very close to the ground, the mechanic, pilot, or other person taking the sample usually lies down under the aircraft or crouches or squats down to open and close the valve in order to take the sample.
Prior to the present invention, the method followed by the person taking the sample was to place a catch basin or other receptacle on the deck under the aircraft in alignment with the drain valve, to lie or crouch down under the fuselage, and to reach up with a wrench and engage the valve handle or knob of the valve. The wrench would then be turned to open the valve and allow the small quantity of fuel to flow or drain down into the receptacle, and subsequently the valve would be closed. Unfortunately, however, this method Invariably also caused the draining fuel to run down the wrench onto the person's hand(s) and arm(s) and clothing while the wrench was being held on the valve during draining of fuel and during opening and closing of the valve. Until the subject invention, the described method, although unsatisfactory, was tolerated as the only method available to sample the fuel. Not only does this method require a special clean-up, contact of the fuel with the skin may be harmful or irritating.
Although a satisfactory tool for obtaining a sample of fuel from a helicopter fuel tank has not been previously known, tools have been available for bleeding air bubbles from hydraulic brake systems, such as used in automobiles. The U.S. Pats. Nos. 3,809,359 and 4,905,731 disclose such brake bleeder tools. These tools have general features in common with the tool of the present invention, but they are not satisfactory for taking the fuel samples as above described. In contrast, the tool of the present invention is especially suited for the task of draining aircraft fuel from helicopters, and perhaps other aircraft, or from any tank supported above the ground, floor or deck, that holds various other liquids, where the drain valve is at the bottom or sump of the tank, so that when the valve is opened, the liquid drains down out of the valve.